From f622bf0d79a7460cb160207bcd75f257deb872ea Mon Sep 17 00:00:00 2001
From: Aleksa Vuckovic <aleksav013@gmail.com>
Date: Thu, 4 Aug 2022 09:00:14 +0200
Subject: drawing characters to fb; fixed draw_line

---
 kernel/graphics.c | 58 +++++++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 46 insertions(+), 12 deletions(-)

(limited to 'kernel/graphics.c')

diff --git a/kernel/graphics.c b/kernel/graphics.c
index da5ed5d..d27a3e3 100644
--- a/kernel/graphics.c
+++ b/kernel/graphics.c
@@ -1,38 +1,42 @@
 #include <stdint.h>
 #include <multiboot2.h>
 #include <graphics.h>
-#include <debug.h>
+#include <font.h>
 
 uint64_t* pixel_offset(fb_t fb, uint32_t x, uint32_t y)
 {
-	return (uint64_t*)((uint32_t*)fb.addr + y * fb.pitch / 4 + x);
+	return (uint64_t*)((char*)fb.addr + y * fb.pitch + x * fb.bpp / 8);
 }
 
 void fb_draw_pixel(fb_t fb, uint32_t x, uint32_t y, uint32_t col)
 {
-	uint64_t* fb_offset = pixel_offset(fb, x, y);
+	if (x >= fb.width || y >= fb.height) return;
+
+	uint32_t* fb_offset = (uint32_t*)pixel_offset(fb, x, y);
 	*fb_offset = col;
 }
 
+/* https://en.wikipedia.org/wiki/Bresenham%27s_line_algorithm */
+
 void fb_draw_line_low(fb_t fb, uint32_t x0, uint32_t y0, uint32_t x1, uint32_t y1, uint32_t col)
 {
-	uint32_t dx = x1 - x0;
-	uint32_t dy = y1 - y0;
-	uint32_t yi = 1;
+	int32_t dx = x1 - x0;
+	int32_t dy = y1 - y0;
+	int32_t yi = 1;
 	if (dy < 0) {
 		yi = -1;
 		dy = -dy;
 	}
-	uint32_t D = (2 * dy) - dx;
-	uint32_t y = y0;
+	int32_t D = (2 * dy) - dx;
+	int32_t y = y0;
 
-	for (uint32_t x = x0; x < x1; x++) {
+	for (int32_t x = x0; x <= x1; x++) {
 		fb_draw_pixel(fb, x, y, col);
 		if (D > 0) {
 			y = y + yi;
 			D = D + (2 * (dy - dx));
 		} else {
-			D = D + 2*dy;
+			D = D + 2 * dy;
 		}
 	}
 
@@ -56,12 +60,12 @@ void fb_draw_line_high(fb_t fb, int32_t x0, int32_t y0, int32_t x1, int32_t y1,
 			x = x + xi;
 			D = D + (2 * (dx - dy));
 		} else {
-			D = D + 2*dx;
+			D = D + 2 * dx;
 		}
 	}
 }
 
-uint32_t abs(int64_t val)
+int32_t abs(int32_t val)
 {
 	if (val < 0) return -val;
 	return val;
@@ -81,3 +85,33 @@ void fb_draw_line(fb_t fb, int32_t x0, int32_t y0, int32_t x1, int32_t y1, int32
 			fb_draw_line_high(fb, x0, y0, x1, y1, col);
 	}
 }
+
+void fb_draw_character(fb_t fb, char c, uint32_t x, uint32_t y, uint32_t char_col, uint32_t bg_col)
+{
+	uint32_t offset = 32 + c * 16;
+	for (uint32_t i = 0 ; i < 16; i++)
+	{
+		for (uint32_t j = 0 ; j < 8; j++)
+		{
+			if (font[offset + i] & (1 << (7 - j))) {
+				fb_draw_pixel(fb, x + j, y + i, char_col);
+			} else {
+				fb_draw_pixel(fb, x + j, y + i, bg_col);
+			}
+		}
+	}
+}
+
+uint32_t strlen(const char* s)
+{
+	char *p = (char*)s;
+	while (*p) p++;
+	return p - s;
+}
+
+void fb_draw_string(fb_t fb, const char* s, uint32_t x, uint32_t y, uint32_t char_col, uint32_t bg_col)
+{
+	for (uint32_t i = 0; i < strlen(s); i++) {
+		fb_draw_character(fb, s[i], x + i * 8, y, char_col, bg_col);
+	}
+}
-- 
cgit v1.2.3